An embedded system for portable electrochemical detection

An embedded system designed to provide miniaturized electrochemical detection (miniEC) in a handheld package is described. The uniqueness of the system lies in the selection of off-the-shelf components that meet stringent requirements for high performance and low power at low cost. The design incorporates a microfabricated electrode sensor array, a potentiostat for electrochemical tests, a liquid crystal display, a four-key pushbutton interface for user input, memory for data storage and a serial connection for networking. An MSP430 microcontroller with its unparalleled low power capability is programmed to process, display and store the signal. It also transmits data to another input device such as a PC via the serial communication module using an RS232 protocol. The potentiostat applies a potential across the sensor and is also responsible for amplifying and converting the sensor current into a voltage range that the microcontroller can record. The four-button interface allows the user to cycle through the electrochemical test variables to view or change them prior to taking a measurement. The button interface also allows the user to start/stop a measurement, set the time and date, and to view a summary of archived data from previous measurements. A graphical user interface was developed so that the user can also perform these tasks from a PC over the serial communication link. The miniEC is compact (about 80 mm × 65 mm) and powered by a single 1.5 V battery (AAA or AA) and can run, for example on a single AAA battery rated at 1000 mAh continuously for 2 weeks. The design of both the hardware and software is modular, general and flexible such that differentiated products can easily be generated for applications in niche fields within a short development window.